We have similar requirements. I think the license terms state that you are not allowed to use the routing data for commercial delivery routing.
Google also limits the number of requests you can make.
On the other hand, using map data to visualize positions is allowed, as far as I know.
We use commercial map data (PTV) and we plan to use GMaps for visualisation and interaction.
BTW: we put the results from our route server in a time/distance database as a means to cache data.